German, from Simplicius Simplicissimus by Grimmelshausen: "ein Sparren zu viel oder zu wenig" zu haben. To have one rafter too many or too few, like a building that was built wrong. Seems to mean the same thing as "a few cards short of a deck," etc. I found it charming because it acknowledges that an extra rafter would be just as indicative of faulty workmanship as a missing one. There are of course lots of English idioms which use the "a few [components] short of a [complete assembly]" formula to indicate that someone's a little wacky, but it's equally logical to speak of fouling up a finely tuned assembly by adding superfluous components, no? Thank you, Germans.
I wonder what would happen if I simply imported this idea into English and started applying it to our idioms for cray-cray. "That guy sure has an extra card in his deck..."
"Ob sie euch schmecken, unsre Fruechte? -- Aber was geht das die Baeume an!"